From the Guidelines
The surgical technique for an above-knee to below-knee popliteal bypass should utilize autologous great saphenous vein as the preferred conduit, as it has been shown to have improved patency rates compared to synthetic grafts 1. The procedure begins with appropriate anesthesia, typically general anesthesia, followed by proper positioning of the patient supine with slight external rotation of the affected leg. Incisions are made at the above-knee and below-knee locations to expose the popliteal artery segments. After systemic heparinization (typically 5,000-10,000 units IV), the graft is tunneled anatomically along the course of the native artery. Proximal anastomosis is performed first at the above-knee site using 5-0 or 6-0 polypropylene suture in an end-to-side fashion. After confirming good inflow, the distal anastomosis is completed at the below-knee site. The graft is assessed for patency using Doppler ultrasound, and hemostasis is achieved before wound closure. Some key points to consider in the surgical technique include:
- The use of autogenous vein is preferred due to its superior patency rates compared to synthetic grafts 1.
- Preoperative assessment of the adequacy of the great saphenous vein conduit is important when developing a patient-specific revascularization strategy for CLTI 1.
- The goal of revascularization for CLTI is to maximize blood flow to the foot, and direct revascularization is preferred when possible 1. Postoperatively, patients typically receive antiplatelet therapy (aspirin 81-325mg daily) and may require temporary anticoagulation. This procedure is performed to treat peripheral arterial disease causing claudication, rest pain, or tissue loss when the disease involves the popliteal artery, with the anatomical approach offering the advantage of avoiding synthetic material at the knee joint flexion point. It is also important to note that prosthetic conduit is a secondary option for patients with CLTI without suitable saphenous veins who require surgical revascularization 1. In cases where no autogenous vein is available, a prosthetic femoral-tibial bypass, and possibly an adjunctive procedure, such as arteriovenous fistula or vein interposition or cuff, should be used when amputation is imminent 1.
From the Research
Surgical Techniques for Femoropopliteal Bypass
The surgical technique for femoropopliteal bypass involves bypassing the blocked native artery using either a section of the patient's own vein (autologous vein) or an artificial graft, such as polytetrafluoroethylene (PTFE) or Dacron 2.
Graft Types and Patency Rates
- Saphenous vein grafts have been shown to have better patency rates compared to synthetic grafts, such as PTFE and Dacron, in above-knee femoropopliteal bypasses 3, 4, 2.
- The use of heparin-bonded ePTFE grafts has been shown to improve patency rates compared to standard ePTFE grafts in both above-knee and below-knee femoropopliteal bypasses 5.
- The primary patency rates for saphenous vein grafts have been reported to be around 76.6% at 5 years, compared to 59.1% for PTFE/Dacron grafts 4.
- The secondary patency rates for saphenous vein grafts have been reported to be around 83.3% at 5 years, compared to 69.2% for PTFE/Dacron grafts 4.
Factors Affecting Patency Rates
- The use of clopidogrel has been shown to not significantly affect patency rates in femoropopliteal bypass grafts 5.
- The presence of claudication, age, and isolated popliteal artery have been shown to be significant predictors of loss of patency in femoropopliteal bypass grafts 5.
- The use of a distal vein cuff has been shown to improve primary patency rates for below-knee PTFE femoropopliteal grafts 2.